Optimal conditions for the production of sulfated polysaccharide by marine microalga Gyrodinium impudicum strain KG03

Abstract

A marine microalga Gyrodinium impudicum strain KG03 produced sulfated exopolysaccharide designated as p-KG03, which showed a strong antiviral activity against encephalornyocarditis virus (EMCV). To optimize culture conditions for the production of p-KG03, mineral salts, vitamins, plant growth hormones, temperature, pH and light conditions were examined. From this study, M-KG03 medium for the maximum production of p-KG03 was suggested as follows; NH(4)Cl 75 muM, NaH(3)PO(4) 200 muM, NaHCO(3) 50 muM, Na(2)SO(4) 10 muM, FeCl(2).6H(2)O 10 muM, MnCl(2).4H(2)O 0.1 muM, vitamin B(12) 0.75 mug, naphthalene acetic acid (NAA) 7.5 mug and myo-inositol 200 mg per liter of aged sea water. The optimal temperature and pH were 22.5 degreesC and 8.0, respectively. The optimal light conditions of intensity and period were 150 muE m(-2) s(-1) and 16:8 h light:dark cycle. Finally, the cell growth and p-KG03 production were measured in one liter of M-KG03 medium with 1% CO(2) and 50 ml min(-1) of airflow using two liters airlift balloon type photobioreactor (ABTPR). At these optimal conditions, p-KG03 production and cell growth were 134.6+/-5.9 mg l(-1) and 123,076+/-1.597 cells ml(-1), respectively, representing a 7.7 and 5.1 times compared with f/2 medium with Erlenmeyer flask culture (p-KG03 production 17.5+/-1.3 mg l(-1) and cell growth 24,311+/-1,291 cells ml(-1)). (C) 2003 Elsevier B.V. All rights reserved.